1. Field of the Invention
The present invention relates to a magnetic disc device, and more particularly to position estimation and position control of magnetic head. The invention further relates to an inspection of magnetic disc device.
2. Description of the Related Art
In a magnetic disc device used as an external memory device, servo information is written on a recording medium in order to control the head position.
One of such methods is the sector servo system. This is a method of causing the head to follow up an arbitrary track on the basis of the position information from the servo sector provided at the beginning of data region of track.
The servo sector is basically composed of a synchronization unit for detecting the servo sector, a track number unit in which the track number of tack is written, and a burst unit in which the burst number for tracking is written.
Tracking of magnetic head is realized by burst signals detected by the magnetic head. Therefore, the tracking precision depends on the detecting precision of burst signals. That is, magnetic noise occurring in the magnetic head and magnetic recording medium has adverse effects on the tracking precision. It is hence an object to obtain accurate tracking position information by separating the noise superposing on the burst signals.
The invention is devised to achieve the above object.
The control apparatus of magnetic disc device of the invention comprises a position detector for detecting the position of a head in the track width direction from a burst signals, noise measuring means for measuring noise level superposed on the detected position, gain determining means for determining an estimate gain corresponding to the noise level, and an estimator for estimating the state of an actuator.
The control method of magnetic disc device of the invention comprises (a) a step of detecting the position of a head in the track width direction from a burst signal, (b) a step of measuring noise level superposed on the head position, (c) a step of determining an estimate gain corresponding to the noise level, and (d) a step of estimating the state of an actuator.
The recording medium of magnetic disc device of the invention stores program data for executing the control method of magnetic disc.
The inspection apparatus of magnetic disc device of the invention adds the amplitude values of burst signals used in position control of the head, calculates the average of the added amplitude values and the variance value or standard deviation, and inspects the magnetic disc device by the variance value or standard deviation.
The inspection method of magnetic disc device of the invention comprises a step of adding the amplitude values of burst signals used in position control of the head, and a step of calculating the average of the added amplitude values and the variance value or standard deviation, and therefore the magnetic disc device is inspected by the calculated variance value or standard deviation.